1998 S-10-E Electric Truck


EV1 System 110 Inverter/Drive train


Dianostic Trouble Codes


1998 S-10-E Electric Truck
EV1 System 110 Inverter/Drive train


The S10E reported DTC-279 code upon acquisition c2008. Upon
investigation we found r
esistance on the HV (high voltage) negative
battery box connection to the PIM when linked
to chassis ground.  A 200 ohms scale was used for this test.

In the first phase we tested the circuit by “unplugging” all the connectors from
the overall PIM when it was still in the vehicle and continued to get
resistance readings from the HV negative connector to chassis ground.  In
the second phase we removed the PIM from the vehicle, retested
and received the same results.  We then went to the third phase
and, with the PIM out of the vehicle, physically
inspecting the interior of the PIM. Then removed the accessory
modules from the PIM, retesting with each removal.  When we
removed the power
steering control module (PSCM) from the bottom
of the PIM the resistance
reading to chassis cleared.

We subsequently opened the PSCM and retested, seperating the
top half PSCM PCB from the bottom half and reconnecting to the PIM, and the
resistance reading reappeared.  The DTC-279
is now located
to the top half of the PSCM.

After disassembly of the PSCM and retesting the resistance reading
vanished.  We found
that mostlikely one of the two regulator chips had a
fault-to-ground at its
insulated mounting screw.  The insulator was
replaced and the PSCM has been returned to
functioning properly.


-- pictures to follow --